Method of manufacturing organic EL element, organic EL element and organic EL display device

ABSTRACT

A method of manufacturing an organic EL element according to the present invention comprises the steps of forming pixel electrodes ( 801 ), ( 802 ), ( 803 ) on a transparent substrate ( 804 ) and forming on the pixel electrodes by patterning luminescent layers ( 806 ), ( 807 ), ( 808 ) made of an organic compound by means of an ink-jet method. According to this method, it is possible to carry out a high precise patterning easily and in a short time, thereby enabling to carry out optimization for a film design and luminescent characteristic easily as well as making it easy to adjust a luminous efficiency.

FIELD OF THE INVENTION

The present invention relates to a method of manufacturing an organicelectroluminescent (EL) element, an organic EL element, and an organicEL display device.

BACKGROUND ART

An organic EL element is an element which has a configuration in which athin film containing a fluorescent organic compound is held between acathode and an anode. In the organic EL element, electrons and holes areinjected from the respective electrodes into the thin film to generateexcitons through the recombination of the electrons and holes. Theorganic EL element produces luminescence by utilizing emission of light(fluorescence or phosphorescence) at the deactivation of the excitons.

The features of the organic EL element is that it is possible to obtaina high intensity surface luminescence on the order of 100 to 100,000cd/m² at a low voltage of less than 10V, and that it is possible toproduce luminescence of from blue to red y the selection of the kind offluorescent material.

The organic EL element is drawing attraction as a device for realizing alarge area full color display element at a low cost (see, Institute ofElectronics, Information and Communication Engineers (IEICE) TechnicalReport, Vol. 89, No. 106, 1989, p. 49). According to the report, brightluminescence of blue, green and red were obtained by forming aluminescent layer using an organic luminescent material which emitsstrong fluorescence. This fact is considered to mean that it is possibleto realize a high brightness full color display by using an organiccoloring matter which emits strong fluorescence in a thin film state andhas less pin hole defects.

In addition, in Japanese Laid-Open Publication No. Hei 5-78655, there isproposed to use an organic luminescent layer containing a luminescentmaterial which is formed of a mixture of an organic charging materialand an organic luminescent material, thereby obtaining a high brightnessfull color element by preventing quenching due to higher concentrationas well as expanding the latitude in the selection of the luminescentmaterial.

Further, in Appl. Phys. Lett. Vol. 64, 1994, p. 815, it is reported thata white luminescence was obtained by using polyvinyl carbazole (PVK) asa luminescent material and doping it with coloring matters correspondingto three primary colors R, G and B. However, in neither of the abovereferences, the configuration or the method of manufacture of an actualfull color display panel is not shown.

In the organic thin film EL elements using the organic luminescentmaterials described above, in order to realize a full color displaydevice, it is necessary to arrange organic luminescent layers which emitany one of the three primary colors for the respective pixels. However,there is a problem in that a polymer or precursor that forms the organicluminescent layer lacks a sufficient resistance to a patterning processsuch as photolithography, so that it is very difficult to carry outpatterning with highly precision.

Further, when several organic layers are to be formed by a vacuumdeposition method, it takes a long time. Therefore, such a method cannotbe said to be an efficient method of manufacturing the element.

SUMMAY OF THE INVENTION

It is an object of the present invention to provide a method ofmanufacturing an organic EL element which makes it possible to carry outpatterning easily and precisely, can attain optimization of a filmdesign in a simple manner, and has excellent luminescencecharacteristics, as well as to provide an organic EL element and anorganic EL display device.

In order to achieve the above object, the manufacturing method of anorganic. EL element according to the present invention comprises thesteps of forming pixel electrodes on a transparent substrate, forming onthe pixel electrodes by patterning at least one luminescent layer havinga certain color and made of an organic compound, and forming a counterelectrode opposing the pixel electrodes, wherein the formation of theluminescent layers is performed by means of an ink-jet method.

In the present invention, it is preferable that the organic compound isa polymer organic compound. In this case, it is preferable that thepolymer organic compound is a hole injection and transfer type material.Preferably, such a polymer organic compound is a polyparaphenylenevinylene or its derivative or a copolymer which contains at least eitherone of these compounds.

In this connection, when an organic luminescent material itself is not ahole injection and transfer type material, as is the case in theabove-mentioned polymer organic compound, it is possible to add a holeinjection and transfer type material to the luminescent layer inaddition to the luminescent material.

Further, it is also preferred that the at least one luminescent layercomprises three layers having different colors, in which the at leasttwo colors out of the luminescent layers of three colors are patternedby means of an ink-jet method. The three colors are red, green and blue,and it is preferable that the red luminescent layer and the greenluminescent layer are patterned by means of an ink-jet method. In thiscase, it is more preferable that the blue luminescent layer is formed bya vacuum deposition method. Further, it is preferable that the blueluminescent layer is made of an electron injection and transfer typematerial, such as an aluminum quinolinol complex.

In the manufacturing method for the organic EL element according to thepresent invention, it is preferable that at least one luminescent layeris laminated with a hole injection and transfer layer, and it is alsopreferable that a protective film is formed on the counter electrode.

In the manufacturing method for the organic EL element of the presentinvention, it is preferable that the transparent substrate is providedwith thin film transistors for driving respective pixels.

Further, it is preferable that the pixel electrodes are formed into atransparent pixel electrode.

Furthermore, the organic EL element of the present invention is providedwith a transparent substrate, pixel electrodes formed on the transparentsubstrate, at least one luminescent layers having a certain color andmade of an organic compound, the luminescent layer being patterned onthe pixel electrodes by an ink-jet method, and a counter electrodeformed on the luminescent layer.

It is preferable that the organic compound is a polymer organiccompound, and it is more preferable that the polymer organic compound isa hole injection and transfer type material.

Moreover, it is preferable that the polymer organic compound is apolyparaphenylene vinylene or its derivative or a copolymer containingat least one of them.

It is preferred that the at least luminescent layer includes threelayers having different three colors, and it is preferable that twolayers thereof in the luminescent layers of three colors are patternedby an ink-jet method. The three colors are red, green and blue, and itis more preferable that the red luminescent layer and the greenluminescent layer are separately patterned by an ink-jet method. In thiscase, it is more preferable that the blue luminescent layer is formed bya vacuum deposition method.

It is preferable that the blue luminescent layer is made of an electroninjection and transfer material. As for such a blue luminescent layer, alayer containing an aluminum quinolynol complex can be mentioned.

Moreover, it is preferable that at least one luminescent layer islaminated with a hole injection and transfer type layer, and it is morepreferable that a protective film is formed on the cathode.

Furthermore, it is preferable that the pixel electrodes are formed intoa transparent pixel electrode.

Moreover, the organic EL display device according to the presentinvention is characterized in that it includes the organic EL elementdescribed in the above.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view which shows a first embodiment of amanufacturing method for an organic EL element according to the presentinvention.

FIG. 2 is a sectional view which shows a second embodiment of amanufacturing method for an organic EL element according to the presetinvention.

FIG. 3 is a sectional view which shows a third embodiment of amanufacturing method for an organic EL element according to the presentinvention.

FIG. 4 is a sectional view which shows a fourth embodiment of amanufacturing method for an organic EL element according to the presentinvention.

FIG. 5 is a sectional view which shows a fifth embodiment of amanufacturing method for an organic EL element according to the presetinvention.

FIG. 6 is a sectional view which shows an example of the organic ELelement according to the present invention.

FIG. 7 is a sectional view which shows an example of an organic ELdisplay device using the organic EL element according to the presentinvention.

FIG. 8 is a diagram which shows an example of an active matrix typeorganic EL display device using the organic EL element according to thepresent invention.

FIG. 9 is a sectional view which shows an example of a manufacturingmethod of the active matrix type organic EL display device.

FIG. 10 is a perspective view which shows an example of a configurationof a head for an ink-jet method which is used in the manufacturingmethod of the organic EL element according to the present invention.

FIG. 11 is a sectional view of the nozzle part of the head for anink-jet method which is used in the manufacturing method of the organicEL element according to the present invention.

FIG. 12 is a diagram which shows another embodiment of an organic ELdisplay device according to the present invention.

FIG. 13 is a schematic perspective view of an organic EL display deviceaccording to the present invention.

FIG. 14 is a diagram which shows an example of the waveform of thedriving voltage applied to the electrodes.

FIG. 15 is a partial sectional view which shows another embodiment of anorganic EL element according to the present invention.

PREFERRED EMBODIMENTS OF THE INVENTION

In the following, the manufacturing method of the organic EL element andthe organic EL element according to the present invention will bedescribed in detail based on the preferred embodiments shown in theaccompanying drawings.

FIG. 1 shows a first embodiment of the manufacturing method of theorganic EL element according to the present invention. This figure showsthe manufacturing method of a full color organic EL element with threecolors. As shown in the figure, this invention is directed to a methodof manufacturing an organic EL element which comprises a step of formingpixel electrodes 101, 102 and 103 on a transparent substrate(transparent support) 104, a step of patterning luminescent layers 106and 107 which are made of organic compounds on the respective pixelelectrodes, and a step of forming a cathode 113, wherein the method ischaracterized in that the formation of the luminescent layers is carriedout by means of an ink-jet method.

The transparent substrate 104 functions not only as a support but alsoas a surface through which light is taken out. Accordingly, the materialfor the transparent substrate 104 is selected by taking thelight-permeability, thermal stability and the like into consideration.As for examples of the material to be used for the transparentsubstrate, glass, transparent plastic or the like can be mentioned, andamong these materials, a substrate made of glass is particularlypreferable in view of its excellent heat resistance.

In more details, the first, pixel electrodes 101, 102 and 103 are formedon the transparent substrate 104. As for examples of methods of formingthese pixel electrodes, photolithography, vacuum deposition method,sputtering method and pyrosol method can be mentioned. Among thesemethods, the photolithography is particularly preferable. As for thesepixel electrodes, it is preferred that they are formed into transparentpixel electrodes. As for the materials constituting the transparentpixel electrodes, a tin oxide film, an ITO (indium tin oxide) film and acomposite oxide film of indium oxide and zinc oxide can be mentioned.

Next, partitioning walls (banks) 105 are formed to fill the spacesbetween the pixel electrodes.

In this way, it is possible to improve the contrast, to prevent mixingof colors of the luminescent materials, and to prevent light fromleaking between the pixels.

As for the materials constituting the banks 105, no particularlimitation is imposed, if they have a resistance to the solvent for theEL material. For example, organic material such as acrylic resin, epoxyresin, photosensitive polyimide and the like; and inorganic materialsuch as liquid glass and the like can be mentioned. In this regard, itis to be noted that the banks 105 may be formed into a black resistwhich is formed by mixing carbon black and the like into theabove-mentioned material.

As for examples of the forming method for the banks 105,photolithography and the like can be mentioned.

Further, organic luminescent layers are formed respectively on the pixelelectrodes according to a predetermined pattern. In this case, it ispreferable to provide organic luminescent layers with three color types.In this connection, it is preferred that at least one layer among theseorganic luminescent layers is formed by an ink-jet method.

In the embodiment shown in FIG. 1, a red luminescent layer 106 and agreen luminescent layer 107 are formed on the pixel electrodes 101 and102, respectively, by the ink-jet method.

In the above descriptions, the term “ink-jet method” is used to mean amethod of forming a pixel of one of the three primary colors includingred, green and blue or a pixel of at least one color which isintermediate between the primary colors by dissolving or dispersing aluminescent material in a solvent to obtain a discharge liquid and thendischarging the discharge liquid from a head 110 of an ink-jet device109.

According to such an ink-jet method, it is possible to carry out finepatterning in a simple manner and in a short time. Further, it is alsopossible to control easily and freely the luminescent characteristicssuch as color balance and brightness (luminance) by adjusting thethickness of the layer through adjustment of the discharge amount of theink or by adjusting the ink concentration.

When the organic luminescent materials are conjugated polymer precursorsdescribed later, the luminescent layers are formed by discharging theluminescent materials by the ink-jet method to carry out patterning, andthen conjugating (to form a film) the precursor components by heating orirradiation with light or the like.

Next, as shown in FIG. 1, a blue luminescent layer 108 is formed on thered luminescent layer 106, the green luminescent layer 107 and the pixelelectrode 103. In this way, it is possible not only to form layershaving the three primary colors including red, green and blue, but alsoto bury the level differences between the banks 105 and each of the redluminescent layer 106 and the green luminescent layer 107 so as to beflattened.

No particular limitation is imposed upon the forming method for the blueluminescent layer 108, and it is possible to form the layer using thegeneral film forming method known as deposition method or wet method,for instance, or using the ink-jet method.

Further, the blue luminescent layer 108 can be formed of an electroninjection and transfer material such as aluminum quinolynol complex. Inthis case, it is possible to promote the injection and transfer of thecarriers so as to improve the luminous efficiency. Furthermore, whensuch a blue luminescent layer 108 is laminated with red and greenluminescent layers formed of a hole injection and transfer materialdescribed later, it is also possible to inject and transfer theelectrons and the holes from the respective electrodes into theselaminated luminescent layers with appropriate balance, thereby enablingto improve the luminous efficiency.

Moreover, when such a blue luminescent layer 108 is laminated with thered and green luminescent layers made of a hole injection and transfertype material, the function of hole injection and transfer and thefunction of electron injection and transfer can be assigned separatelyto different layers, so that optimum design can be selected for therespective materials. No particular limitation is imposed upon theforming method of such an electron injection and transfer layer, and itis possible to form the layer by using, for example, the general filmforming method known as deposition method or wet method or the ink-jetmethod.

In this connection, as for an organic compound which can form anelectron injection and transfer layer, oxadiazole derivative such asPBD, OXD-8 and the like, DSA, aluminum quinolinol complex, Bebq,triazole derivative, azomethine complex, porphine complex, benzoxadiazoland the like can be mentioned. In this case, an electron injection andtransfer layer can be formed from just one of these materials, or formedby mixing or laminating one of or two or more of them. In addition, theelectron injection and transfer layer may be formed by doping afluorescence dye described later to the organic compound described.Further, the electron injection and transfer layer itself may have afunction of luminescence.

As described above, in this embodiment, organic luminescent layers fortwo colors are formed by the ink-jet method while the layer for theremaining one color is formed by a different method. Therefore,according to this embodiment, even when a luminescent material which isnot so suited for the ink-jet method is used, a full color organic ELelement can be formed by using such a material in a combination withother organic luminescent materials that are suited for the ink-jetmethod, so that the latitude in the design for the EL element will beexpanded.

As for examples of the forming method for the luminescent layer otherthan the ink-jet method, photolithography method, vacuum depositionmethod, printing method, transfer method, dipping method, spin coatingmethod, casting method, capillary method, roll coating method, barcoating method and the like can be mentioned.

Finally, a cathode (a counter electrode) 113 is formed, thereby theorganic EL element of the present invention is completed. In this case,it is preferred that the cathode 113 is formed into a metallic thin filmelectrode, and as for examples of the metal for forming the cathode, Mg,Ag, Al, Li and the like can be mentioned. In addition, a material havingsmall work function can be used for the material for the cathode 113,and for example, alkali metal, alkali earth metal such as Ca and thelike, and alloys containing these metals can be used. Such a cathode 113may be formed using a deposition method, a sputtering method or thelike.

The organic EL element of the present invention is manufactured throughthe processes described in the above. Namely, as shown in FIG. 1, thepixel electrodes 101 and 102 are provided on the transparent substrate104, the red luminescent layer 106 and the green luminescent layer 107which are made of organic compounds are then formed on the pixelelectrodes 101 and 102, respectively, by patterning by using the ink-jetmethod, and then the blue luminescent layer 108 is formed on theluminescent layers 106 and 107 and the pixel electrode 103 by the vacuumdeposition method. Thereafter, the cathode 113 is formed on top of theblue luminescent layer 108, thereby the organic EL element according tothe present invention is completed.

Further, as shown in FIG. 6, a protective film 415 may be formed on topof a cathode 413. By forming such a protective film 415, it becomespossible to prevent deterioration, damage, peeling and the like fromoccurring in the cathode 413 and in the luminescent layers 406, 407 and408.

As for materials for constructing the protective film 415, epoxy resin,acrylic resin, liquid glass and the like can be mentioned. Further, asfor examples of the forming method for the protective film 415, spincoating method, casting method, dipping method, bar coating method, rollcoating method, capillary method and the like can be mentioned.

In this embodiment, it is preferable that these luminescent layers areformed of an organic compound, and it is more preferable that theseluminescent layers are formed of a polymer organic compound. Byproviding such luminescent layers that are formed of the organiccompound, it is possible to obtain high brightness surface luminescenceat low voltages. Further, since luminescent materials can be selectedfrom wide range of field, a rational design for the luminescent elementbecomes possible.

In particular, polymer organic compounds have an excellent filmformation property, and the luminescent layers composed of polymerorganic compounds have an extremely good durability. Further, thesepolymer organic compounds have a band gap in the visible region and arelatively high electrical conductivity. Among such polymer organiccompounds, a conjugated polymer can exhibit such properties prominently.

As for materials for the organic luminescent layers, polymer organiccompound itself, precursor of conjugated organic polymer compound whichis to be conjugated (to form a film) by heating or the like, and othermaterials are used.

When a precursor prior to conjugation (to form a film) is used as aluminescent material, the viscosity or the like of a discharge liquidused for the ink-jet system can be adjusted easily, so that thepatterning is carried out precisely and the luminescence characteristicsand the film properties of the luminescent layer can be controlledeasily.

It is preferred that the polymer organic compound forming theluminescent layers is a hole injection and transfer material. In thisway, it is possible to promote the injection and transfer of thecarriers and thereby to improve the luminous efficiency.

As for examples of an organic compound which can form the luminescentlayers, polyalkylthiophene such as PPV (poly(paraphenylene vinylene)) orits derivative, PTV (poly(2,5-thienylene vinylene)) and the like;polyallylene vinylene such as PFV (poly(2,5-furylene vinylene))polyparaphenylene, polyalkylfluorene and the like; pyrazoline dimer;quinolizine carboxylic acid; benzopyrylium perchlorate;benzopyranoquinolizine; rubrene; phenanthroline europium complex and thelike can be mentioned. In this case, just one of them or a mixture oftwo or more of them can be selectively used.

Among these organic compounds, PPV which is a conjugated organic polymercompound or its derivative is preferable. The precursor prior toconjugation (to form a film) of PPV or its derivative is soluble towater or organic solvent, so that they are suitable for patternformation by the ink-jet method. Further, it is possible to obtain athin layer which has high optical quality and excellent durability,since it is a polymer. Furthermore, PPV or its derivative possesses astrong fluorescence, and since it is a conductive polymer in whichπ-electron of double bond is delocalized on the polymer chain, a thinfilm of PPV also functions as a hole injection and transfer layer, whichmakes it possible to obtain an organic EL element having highperformance.

Furthermore, the composition for an organic EL element in a case where apolymer organic compound is used for the material for the luminescentlayers may include at least one kind of fluorescent dye in it. Byincluding such fluorescent dye way, it becomes possible to change theluminous property of the luminescent layer. Therefore, the addition ofthe fluorescent dye is effective as a means, for example, for improvingthe luminous efficiency of the luminescent layer or for changing themaximum wavelength of light absorption (emitted color) of theluminescent layers.

Namely, a fluorescent dye can be utilized not only as a material for theluminescent layers but also as a material for the coloring matter whichhas the luminescence function itself. For example, almost all of theenergy of the excitons which are generated by the recombination ofcarriers on the molecules of a conjugated organic polymer compound suchas PPV can be transferred onto the molecules of the fluorescent dye. Inthis case, the current quantum efficiency of the EL element is alsoincreased, because the luminescence arises only from the molecules ofthe fluorescent dye which have a high fluorescence quantum efficiency.Accordingly, by the addition of a fluorescent dye into the compositionfor the organic EL element, the luminescence spectrum of the luminescentlayer becomes at the same time the spectrum of the fluorescent dye,whereby this method becomes also an effective means for changing theemitted color.

In this connection, it should be noted that what is meant here by thecurrent quantum efficiency is a scale for considering the luminescenceperformance according to the luminescence function, and it is defined bythe following expression.

-   -   η_(ε)=energy of emitted photon/input electrical energy.

The changes in the maximum wavelength of light absorption induced by thedoping of a fluorescent dye make it possible, for example, to emit thethree primary colors of red, green and blue, thereby enabling to obtaina full color display device.

Further, the doping of the fluorescent dye makes it possible to improveextremely the luminous efficiency of the EL element.

As for a fluorescent dye used for the red luminescent layer, laser dyeDCM, rhodamine or a rhodamine derivative, perylene and the like can beused. These fluorescent dyes are soluble to solvents because they arelow molecules, and have a high compatibility with PPV or the like, sothat a luminescent layer with a good uniformity and good stability canbe formed easily. As for examples of the rhodamine derivativefluorescent dyes, rhodamine B, rhodamine B base, rhodamine 6G, rhodamine101 perchlorate can be mentioned. In this case, a mixture of two or moreof them can be selectively used.

Further, as for a fluorescent dye used in the green luminescent layer,quinacridone, rubrene, DCJT and their derivatives can be mentioned.Since these fluorescent dyes are low molecules in the same manner as thefluorescent dyes to be used in the above-mentioned red luminescentlayer, they are soluble to solvents and have a high compatibility withPPV or the like, so that the luminescent layer can be formed easily.

As for the fluorescent dye used in the blue luminescent layer,distyrylbiphenyl and its derivative can be mentioned. These fluorescentdyes are soluble to aqueous solutions in the same manner as theabove-mentioned fluorescent dyes for the red luminescent layer, and havehigh compatibility with PPV or the like, so that the luminescent layercan be formed easily.

In addition, as for other fluorescent dyes that can be used in the blueluminescent layer, coumarin; and coumarin derivatives such ascoumarin-1, coumarin-6, coumarin-7, coumarin 120, coumarin 138, coumarin152, coumarin 153, coumarin 311, coumarin 314, coumarin 334, coumarin337, coumarin 343 and the like can be mentioned.

Moreover, as for other luminescent materials that can be used in theblue luminescent layer, tetraphenylbutadiene (TPB) or TPB derivative,DPVBi and the like can be mentioned. Since these luminescent materialsare also low molecules in the same manner as the fluorescent dyes forthe red luminescent layer, they are soluble to solvents, and have highcompatibility with PPV or the like so that the luminescent layer can beformed easily.

These fluorescent dyes and luminescent materials as described above canbe selectively used as a just one of them or as a mixture of two or moreof them.

The structure of a head of the ink-jet system used in the manufacturingmethod of the organic EL element according to the present invention isshown in FIG. 10 and FIG. 11.

The head 10 for the ink-jet system is provided with, for example, astainless steel nozzle plate 11 and a vibration plate 13, and they arecoupled via partitioning members (reservoir plates) 15.

Between the nozzle plate 11 and the vibration plate 13, a liquid storage21 and a plurality of spaces 19 are formed by means of the reservoirplates 15. The inside of the respective spaces 19 and the liquid storage21 are filled with the composition according to the present invention,and the spaces 19 communicate with the liquid storage 21 through supplyports 23.

Further, a nozzle hole 25 is provided in the nozzle plate 11 fordischarging the composition in a jet-form from the spaces 19. In themeantime, a hole 27 is formed in the vibration plate 13 for supplyingthe composition to the liquid storage 21.

Further, on a surface of the vibration plate 13 which is opposite to theother surface that faces with the spaces 19, piezoelectric elements 29are attached at positions corresponding to the positions of therespective spaces 19.

Each of the piezoelectric elements 29 is positioned between a pair ofelectrodes 31. The piezoelectric element 29 is adapted to bend so as toprotrude outward when energized, and at the same time, the vibrationplate 13 to which the piezoelectric element 29 is attached is also bentoutward together with the piezoelectric element 29. In this way, thevolume of the space 19 is increased. With this result, a quantity of thecomposition corresponding to the increased volume flows into the space19 from the liquid storage 21 through the supply port 23.

Next, when the piezoelectric element is de-energized, both thepiezoelectric element 29 and the vibration plate 13 return to theiroriginal shapes. In this way, the space 19 also returns to its originalvolume, so that the pressure exerted to the composition within the space19 goes up, whereby the composition is jetted out from the nozzle hole25 toward the substrate.

In this connection, a water repellent layer 26 is formed at theperipheral part of the nozzle hole 25 in order to prevent the bend ofthe jetted direction of the composition and the clogging of the holefrom occurring.

Namely, a water repellent layer 26 formed of, for example, aNi-tetrafluoroethylene eutectoid plated layer is provided in theperipheral part of the nozzle hole 25 as shown in FIG. 11.

Using the head with the above construction, it is possible to formrespective organic luminescent layers by discharging the compositionscorresponding to, for example, the three primary colors red, blue, andgreen according to a predetermined pattern, thereby enabling to form thepixels.

In the manufacturing method of the organic EL element according to thepresent invention, compositions with the following characteristics canbe used as organic luminescent materials for the ink-jet method.

It is preferable that the compositions have a contact angle of 30 to 170degrees, and more preferably, 35 to 65 degrees, with respect to thematerial constituting the nozzle surface 251 of the nozzle provided inthe head for the ink-jet system for discharging the composition. Whenthe composition has the contact angle given in this range, it ispossible to carry out a precise patterning by suppressing the bend inthe jetted direction of the composition.

Namely, if the contact angle is less than 30 degrees, wettability of thecomposition with respect to the material constituting the nozzle surfaceincreases, so that there is a case that the composition attachesasymmetrically to the periphery of the nozzle hole at the time ofdischarging the composition. In this case, an attraction acts betweenthe composition attached to the nozzle hole and the composition to bedischarged. This causes the discharge of the composition by anon-uniform force, which gives rise to a situation so-called “bend inthe jetted direction” in which the composition is unable to reach thetarget position, and also to an increase in the occurrence frequency ofthe bend in the jetted direction. Meantime, if the contact angle exceeds170 degrees, the interaction between the composition and the nozzle holebecomes a minimum and the shape of the meniscus at the tip of the nozzleis unstable, so that the control of the amount and the timings ofdischarge of the composition tends to be difficult.

In the above descriptions, what is meant here by the bend in the jetteddirection refers to a situation in which, when the composition isdischarged from the nozzle, the point of impact of a dot deviates fromthe target position by more than 50 μm. Further, the occurrencefrequency of the bend in the jetted direction is defined as the timeuntil the bend in the jetted direction occurs after a continuousdischarge of the composition is started at the frequency of 7200 Hz. Thebend in the jetted direction is generated principally by such causes asthe nonuniformity in the wettability of the nozzle hole and the cloggingof the nozzle hole by the attachment of solid components of thecomposition. Such bend in the jetted direction can be eliminated bycleaning the head. In this connection, more frequent head cleaning isrequired for more frequency of occurrence of the bend in the jetteddirection, and such a composition that arises the higher occurrencefrequency can be said to a composition that deteriorates themanufacturing efficiency of the EL element by the ink-jet method. On thepractical level, an occurrence frequency of the bend in the jetteddirection is required to be more than 1000 seconds.

By preventing such bend in the jetted direction from occurring, itbecomes possible to carry out a highly fine patterning with highprecision.

Further, it is preferable that the viscosity of the composition is 1 to20 cp, and more preferably 2 to 4 cp. If the viscosity of thecomposition is less than 1 cp, the contents of the precursor and thefluorescent dye in the material are too small, so that the luminescentlayer which is formed cannot exhibit luminescence power sufficiently. Onthe other hand, if it exceeds 20 cp, it is impossible to discharge thecomposition smoothly from the nozzle, and it becomes difficult to carryout patterning unless otherwise such a change in the specification asthe enlargement of the diameter of the nozzle hole is introduced. Inaddition, when the viscosity of the composition is high, precipitationof the solid components in the composition tends to occur, thus leadingto an increased occurrence frequency of clogging of the nozzle hole.

Furthermore, it is preferable that the composition has the surfacetension of 20 to 70 dyne/cm, and more preferably 25 to 40 dyne/cm. Byrestricting the surface tension to such a range, it is possible tosuppress the bend in the jetted direction and suppress the occurrencefrequency of the bend in the jetted direction to a low level, in thesame manner as the case of the above-mentioned contact angle. If thesurface tension is less than 20 dyne/cm, the wettability of thecomposition with respect to the material constituting the nozzle surfaceincreases, which results in the occurrence of the bend in the jetteddirection, and an increase in the occurrence frequency of the bend inthe jetted direction, similar to the case of the contact angle. On theother hand, if it exceeds 70 dyne/cm, the shape of the meniscus at thetip of the nozzle is not stable, which results in the difficulty in thecontrol of the amount and the timings of discharge of the composition.

Further, as for the composition of the organic luminescent materialsuitable for the manufacturing method of the organic EL element of thisinvention, it needs to satisfy the condition on the numerical range forat least one of the characteristics including the contact angle, theviscosity and the surface tension described above. In this connection, acomposition which satisfies the conditions for the arbitrary combinationof two characteristics is more preferable, and a composition whichsatisfies the conditions for all the characteristics is most preferable.

FIG. 2 shows a second embodiment of the manufacturing method of theorganic EL element according to the present invention.

In this second embodiment, after formation of pixel electrodes 201, 202and 203 and banks 205 on a transparent substrate 204, a red luminescentlayer 206 and a green luminescent layer 207 are formed by using anink-jet method in the same manner as the first embodiment.

This second embodiment is different from the first embodiment in thepoint that a hole injection and transfer layer 208 is formed on thepixel electrode 203 and then a blue luminescent layer 210 is laminatedon the layer 208. By the lamination of the hole injection and transferlayer 208 with the blue luminescent layer, it becomes possible topromote the injection and transfer of the holes from the electrode toimprove the luminous efficiency as mentioned above.

Thus, in the manufacturing method for the organic EL element accordingto the present invention, it is preferable to laminate a hole injectionand transfer layer with at least one luminescent layer with a certaincolor. In this way, it is possible to improve the luminous efficiencyand to improve the stability of the thin film element itself.

In this case, at the vicinity of the interface between the luminescentlayer and the hole injection and transfer layer which are laminated witheach other, a part of the materials contained in either of layers mayexist in the state of mutual impregnation and diffusing into the otherlayer.

It is preferable that the hole injection and transfer layer 208 is anon-luminescent layer. With this arrangement, it is possible to make aregion of the blue luminescent layer 210 positioned above the pixelelectrode 203 to be a luminescent portion, thereby enabling to fabricatea full color organic EL element more easily.

No particular limitation is imposed upon the forming method for such ahole injection and transfer layer 208, but for example, it is possibleto form the layer by using the ink-jet method. In this way, it becomespossible to arrange the hole injection and transfer layer 208 preciselywith a predetermined pattern.

As for examples of the material constituting the hole injection andtransfer layer 208, aromatic diamine based compound such as TPD; MTDATA;quinacridone; bisstil anthracene derivative; PVK (polyvinyl carbazole);phthalocyanine based complex such as copper phthalocyanine; porphinbased compound; NPD; TAD; polyaniline; and the like can be mentioned.Among these materials, PVK is particuraly preferred. By using PVK, itbecomes possible to form a non-luminescent hole injection and transferlayer.

Further, the organic EL element according to the present invention canbe obtained by forming a blue luminescent layer 210 and a cathode 211 inthe same way as the first embodiment. The materials constituting theblue luminescent layer 210 and the cathode 211 and the manufacturingmethod thereof are the same as those of the first embodiment.

FIG. 3 shows a third embodiment of the manufacturing method for theorganic EL element according to the present invention.

In this third embodiment, after the formation of pixel electrodes 301,302 and 303 and banks 305 on a transparent substrate 304, a redluminescent layer 306 and a green luminescent layer 307 are formed inthe same manner as the first embodiment.

Next, a hole injection and transfer layer 308 is formed on the entiresurface of the red luminescent layer 306, the green luminescent layer307 and the pixel electrode 303. By laminating the hole injection andtransfer layer 308 with the luminescent layers 306 and 307 in this way,it is possible to promote the injection and the transfer of the holesfrom the electrodes to improve the luminescence efficiency, as describedin the above.

Further, by the same reason as in the above, it is preferable that thehole injection and transfer layer 308 is formed into a non-luminescentlayer.

No particular limitation is imposed upon the forming method for the holeinjection and transfer layer 308, and for example, ink-jet method,vacuum deposition method, dipping method, spin coating method, castingmethod, capillary method, roll coating method, bar coating method andthe like can be mentioned. In this embodiment, it is to be noted thatthe hole injection and transfer layer can be formed using the vacuumdeposition method. In this connection, as for the material constitutingthe hole injection and transfer layer 308, the same materials as thosementioned in the second embodiment can be used.

Further, by forming a blue luminescent layer 309 and a cathode 311 onthe hole injection and transfer layer 308, the organic EL elementaccording to the present invention can be obtained. The constituentmaterial and the forming method of the cathode 311 are the same as thoseof the above-mentioned embodiments.

FIG. 4 shows a fourth embodiment of the manufacturing method for theorganic EL element according to the present invention.

In this fourth embodiment, after the formation of pixel electrodes 801,802 and 803 and banks 805 on a transparent substrate 804 in the same wayas the first embodiment, luminescent layers 806, 807 and 808 arepatterned on the pixel electrodes 801, 802 and 803, respectively, by theink-jet method. In this way, the amount of the material to be dischargedfor the respective luminescent layers, the number of times of thedischarge and the formation pattern of the luminescent layers, forexample, can be adjusted easily and handily, so that the luminescentcharacteristics and film thickness and the like of the respectiveluminescent layers can be controlled easily.

In addition, an electron injection and transfer layer 811 is formed onthe luminescent layers 806, 807 and 808. The electron injection andtransfer layer 811 facilitates the injection of the electrons from thecathode, and contributes to the prevention of electrode extinction bykeeping the luminescent portions away from the cathode to establish abetter contact with the cathode. As for the electron injection andtransfer layer 811, aluminum quinolynol complex to which the doping isnot carried out can be used. This electron injection and transfer layer811 can be formed by means of a vacuum deposition method.

In this connection, the forming method for the electron injection andtransfer layer 811 is not limited to this method, and for example, theink-jet method, vacuum deposition method, dipping method, spin coatingmethod, casting method, capillary method, roll coating method, barcoating method or the like can be used.

Further, the organic EL element according to the present invention canbe obtained by forming a cathode 813 on top of it. The constituentmaterial and the formation method of the cathode 813 are the same asthose of the above-mentioned embodiments.

FIG. 5 shows a fifth embodiment of the manufacturing method of theorganic EL element according to the present invention.

In this fifth embodiment, pixel electrodes 801, 802 and 803 are firstformed on a transparent substrate 804 in the same manner as the firstembodiment. Then, a hole injection and transfer layer 815 which is forexample made of PVK is formed on the entire surfaces of the pixelelectrodes by means of, for example, a spin coating method. Accordingly,since the hole injection and transfer layer 815 in this embodiment canbe formed by means of coating without need of patterning, it is possibleto increase manufacturing efficiency.

No particular limitation is imposed upon the forming method for the holeinjection and transfer layer 815, and for example, ink-jet method,vacuum deposition method, dipping method, spin coating method, castingmethod, capillary method, roll coating method, bar coating method andthe like can be used.

Further, from the same reason described above with reference to theother embodiments, it is preferred that the hold injection and transferlayer 815 is formed into a non-luminescent layer.

On top of the hole injection and transfer layer 815, luminescent layers806, 807 and 808 are formed. In this regard, it is preferred that amongthese luminescent layers, at least one luminescent layer for a certaincolor is formed by pattering using the ink-jet method carried by theink-jet device 809.

Then, by forming a cathode 813 on top of the luminescent layers, anorganic EL element according to the present invention can be obtained.The structural material for the cathode 813 and the manufacturing methodthereof are the same as those of the other embodiment described above.

According to this fifth embodiment, no bank is formed. However, by usingthis manufacturing method, the coating of the luminescent layers for theprimary colors R, G and B can be carried out correctly and preciously,thus leading to improvement of manufacturing efficiency. In this regard,it is to be noted that the manufacturing method of this embodiment canbe also applied to the case where banks are provided to form respectivepixels like the previous embodiments.

The organic EL element of the present invention can be manufacturedaccording to the manufacturing methods described above with reference tothe embodiments. However, the present invention is not limited to thestructures provided by these methods, and the following structures canbe adopted, for instance.

FIG. 15 is a partial cross-sectional view which shows other embodimentof an organic EL element according to the present invention.

The organic EL element of this embodiment has a construction in which areflection layer 62, a transparent conductive film (ITO film) 63, a holeinjection and transfer layer 64, an organic luminescent layer 65, ametal layer 66 and a transparent conductive layer (ITO film) 67 arelaminated on a transparent substrate 61 in this order. Hereinbelow, thematerials and the manufacturing methods of the respective layers (films)are described, in which a description is made only for the differencesfrom the previous embodiments and the common explanation is omitted.

In the organic EL element according to this embodiment, on thetransparent substrate 61, the reflection layer 62 which is made from ametal thin film such as Al is provided directly.

The metal layer 66 which is laminated onto the luminescent layer 65 as acathode is extremely thin (approximate to 10 to 50 Å), so that the metallayer has a light permeability so as to pass emitted light from theluminescent layer 65 therethrough. On the other hand, since the metallayer is extremely thin, its value of resistance is high and thereforeits conductivity is insufficient. Therefore, the metal layer can notsufficiently exhibit function as the cathode. For this reason, thetransparent conductive film (ITO film) 67 is laminated onto the metallayer 66. In this connection, it is to be noted that such a metal layer66 can be made from Al—Li alloy or the like for example, and it can beformed using the vacuum deposition method, sputtering method or thelike.

By using the above described construction, light which is converted inthe luminescent layer 65 from a current which has been injected from theelectrodes is transmitted in the direction indicated by the arrow in thedrawing. With this result, it becomes possible to take out the lightwithout passing through the transparent substrate 61, so that a displaywith a higher brightness becomes possible.

FIG. 7 is an illustration which shows an embodiment of an organic ELdisplay device according to the present invention.

In this embodiment, a bus line (gate line) 511 made of Al is formed on aglass plate 501 by means of a photolithography patterning method, and athin film transistor (not shown in the drawing) is formed thereon toconstitute the ITO transparent pixel electrode 504 and the like. Then,as is the same manner as the first embodiment, a red luminescent layer502 and a green luminescent layer 503 are formed by means of the ink-jetmethod, and then a blue luminescent layer 505 is formed by means of thevacuum deposition method. Thereafter, a cathode 506 is formed by meansof the vacuum deposition method, thereby constructing the organic ELelement same as the first embodiment described above.

In addition, a protective base material 507 is stuck onto thetransparent substrate 501 in a fixed manner by means of a peripheralseal 509.

Next, this assembly is placed in an inert gas atmosphere such as argongas or the like, and thereby introducing the inert gas inside thereoffrom a seal opening 513 and then the seal opening 513 is sealed with aseal member 508. By filing the inside of the assembly with the inert gas51 and then sealing it, as described above, it becomes possible toprotect the organic EL element from external contamination such asmoisture or environmental changes, thereby enabling to maintain theluminescent characteristics of the organic EL display device. In thiscase, it is preferred that the seal member 508 is formed form a materialthrough which the inert gas 512 does not penetrate.

A silver paste 510 has a function that realizes a contact between thecathode 506 and the gate line 511 on the element.

Gate lines 511 are provided to control ON and OFF of the thin filmtransistors (TFT), which are provided in the respective display pixels,in each line of the pixels in order to select pixels to be displayed.Upon writing, potential of the gate line for one line of pixels isturned into a selected level, thereby bringing the TFTs on this lineinto a conductive state. At this time, by supplying picture signals forthe corresponding pixels from the source electrode wires of therespective lines (not shown in the drawing), the voltages of the picturesignals are applied to the pixel electrodes through the TFTs, therebyenabling to charge the potentials to the pixels to a level of a signalvoltage and then discharge them.

FIG. 8 is an illustration which shows other embodiment of an activematrix type organic EL display device using the organic EL elementaccording to the present invention. This organic EL display device ofthis embodiment includes an pixel arrangement comprised of a pluralityof luminescent pixels which are arranged in a matrix form and which areformed into any one of R, G and B luminescent elements.

As shown in this figure, on the substrate (not shown), there areprovided signal lines (signal electrodes) 601 and gate lines (gateelectrodes) 602 which are arranged in a matrix form so as to beorthogonal to each other. Further, in each of the pixels, a thin filmtransistor (TFT) 604 which is connected to both the signal line 601 andthe gate line 602 is provided, and a luminescent layer 605, 606 which isformed of the organic EL element and connected to the TFT is laminatedon the TFT. In this case, at least one luminescent layer for any one ofcolors R, G, B is formed by means of the ink-jet method.

FIG. 9 is a sectional view which shows one example of the manufacturingmethod of the active matrix type organic EL display device according tothe present invention.

First, on a transparent substrate 904, predetermined thin filmtransistors 915 as well as gate lines and signal lines (not shown) andthe like are formed. Next, on respective pixel electrodes (ITO) 901,902, 903 which are respectively provided with prescribed functionalelements such as the thin film transistors 915, hole injection andtransfer layers 911 are formed so as to cover the respective pixelelectrodes. As for the hole injection and transfer type material, thesame materials that are discussed in this specification with referenceto the previous embodiments can be used. Further, the method of formingthe hole injection and transfer layer 911 is not limited to a specificmethod, and it is possible to form the layer by means of any methoddescribed above.

Further, respective luminescent layers 906 (red), 907 (green) and 908(blue) are formed by patterning. In the formation of these luminescentlayers, at least one layer for one color is formed by the ink-jet methodusing an ink-jet device 910.

Finally, a reflection electrode 913 is formed, thereby completing theorganic EL display device according to the present invention. As for thereflection electrode 913, Mg—Ag electrode having a thickness of about0.1 to 0.2 μm or the like is formed, for instance.

In the above-mentioned embodiment concerning the active matrix typeorganic EL display device according to the present invention, a thinfilm transistor is used as a switching element, but the presentinvention is not limited thereto. Other switching elements andtwo-terminal element such as MIM can be used. Further, the displaydevice may be configured into a passive drive type or a static drivetype (static image, segment display).

Furthermore, the number of the switching element is not limited to oneper one pixel. A plurality of switching elements may be provided per onepixel.

FIG. 12 shows an embodiment of an organic EL display device in which aplurality of switching elements are provided per one pixel. In thisembodiment, a switching type thin film transistor 142 carries out a rolethat transmits the potential at a signal electrode 132 to a current thinfilm transistor 143 in response to the potential at a scanning electrode131, and the current thin film transistor 143 carries out a role thatcontrols electrical connection between the common electrode 133 and thepixel electrode 141.

Next, referring to the drawings, a description is made with regard to anembodiment of a passive matrix type (simple matrix type) organic ELdisplay device using the organic EL element according to the presentinvention.

FIG. 13 is a perspective view which roughly shows a structure of theorganic EL display device according to the present invention.

As shown in the drawings, in the organic EL display device of thisembodiment, a scanning electrode 53 and a signal electrode 54 which areformed into an elongated strip, respectively, are arranged outside theorganic EL element 52 so that scanning lines extending from the scanningelectrode 53 and the signal lines extending from the signal electrode 54are orthogonal to each other through the organic EL element.

Such a passive matrix type display device is driven by selectingscanning lines of the scanning electrode 53 in a pulsed manner in asequential order while a voltage is applied to signal lines of thesignal electrode 54 corresponding to pixels to be displayed on thescanning line. Such selection of the lines is carried out by acontroller 55.

In this connection, it should be noted that in a case of the passivedrive type display device, it is necessary that a cathode is patternedso as to be separate forms to correspond to each of lines. For example,when a thin cathode having a thickness of about 0.2 μm is formedaccording to the third embodiment, such separate forms of the cathodecan be automatically obtained since the cathode is separated by thebanks.

Such a cathode is formed by the patter formation performed by a maskingdeposition method or a laser cutting method, for instance.

FIG. 14 is a diagram which shows one example of wave forms of drivingvoltages applied to the scanning electrode 13 and signal electrode 14,respectively. The wave forms shown in the drawing are determined so asto be able to apply a voltage Vs which is sufficient to luminescence toselected pixels. Further, the brightness of a pixel to be displayed iscontrolled through the width of the pulse from the signal electrode 14that has been determined so as to meet with a gray scale of thebrightness to be displayed. On the other hand, a voltage Vn which islower than a luminescent threshold voltage is applied to respectivenon-selected pixels.

In FIG. 14, Tf shows a scanning timing. In this case, the scanningsignal is driven by a pulse having a duty ration of 1/100. In thisconnection, it has been confirmed that the luminescence of the blueluminescent layer 808 of the organic EL display device comprised of theorganic EL elements of the fourth embodiment was a brightness of 100cd/m2 at a driving voltage of 20V.

EXAMPLES <Manufacturing of Organic EL Elements> Example 1

As shown in FIG. 1, on the glass substrate 104, ITO transparent pixelelectrodes 101, 102 and 103 were formed by means of photolithography soas to form a pattern having a pitch of 100 μm and a thickness of 0.1 μm.

Then, the spaces between the ITO transparent pixel electrodes wereburied, and then banks 105 which act not only as a light cut-off layerbut also an ink drop preventing wall were formed by photolithography. Inthis case, the banks 105 were designed so as to have a width of 20 μmand a thickness of 2.0 μm.

Further, after the pattern formation with red and green luminescentmaterials shown in Table 1 and Table 2 which were jetted from the head110 of the ink-jet device 109, they were undergone heat treatment undera nitrogen atmosphere for hours to polymerize the precursors in thecompositions of the materials, thereby forming luminescent layers 106(red) and 107 (green).

Then, by carrying out a vacuum deposition of aluminum quinolynol complexto which perylene condensed aromatic was added as a dopant, a blueluminescent layer 108 of the electron injection and transfer type havinga thickness of 0.1 μm was formed.

At the last, a Mg—Ag electrode 113 having a thickness of 0.8 μm wasformed as a cathode using a vacuum deposition method to obtain anorganic EL element.

Example 2

In the same manner as Example 1, ITO transparent pixel electrodes 201,202, 203 were formed on a glass substrate 204 as shown in FIG. 2.Thereafter, the spaces between the ITO transparent pixel electrodes wereburied and then resists (partitioning walls) 205 made of alight-sensitive polyimide and functioning not only as a light cut offlayer but also an ink drop preventing wall were formed.

Then, after coating and pattern formation of read and green luminescentmaterials shown in Table 1 and Table 2, respectively, by using anink-jet device 209 in the same way as the Example 1, they were undergoneheat treatment under a nitrogen atmosphere for four hours to polymerizethe precursors in the compositions of the materials, thereby formingluminescent layers 206 (red) and 207 (green).

Next, a hole injection and transfer layer made of polyvinyl carbazole(PVK) was patterned on the transparent pixel electrode 203 by means ofthe ink-jet device 209. Then, a blue luminescent layer 210 was formed bycoating the pyrazoline dimer on top of the hole injection and transferlayer.

Finally, an Al—Li electrode 211 having the thickness of 0.8 μm wasformed as the cathode by the deposition method, and thereby the organicEL element was manufactured.

Example 3

First, ITO transparent pixel electrodes 801, 802 and 803 and banks 805were formed on a glass substrate 804 as shown in FIG. 4 in the same wayas Example 1.

Next, an organic hole injection and transfer type material was mixed inthe luminescent materials shown in Table 1 and Table 2 to formluminescent layers 806 (red), 807 (green) and 808 (blue) by using anink-jet device 809.

Next, the vacuum deposition was carried out using the aluminumquinolynol complex to which the doping was not carried out to form anelectron injection and transfer layer 811 having the thickness of 0.1μm.

Finally, an Al—Li electrode 813 having the thickness of 0.2 μm wasformed as the cathode by the deposition method, and thereby the organicEL element was manufactured.

Example 4

In the same way as Example 1, ITO transparent pixel electrodes 301, 302and 303 and banks 305 were formed on a glass substrate 304 as shown inFIG. 3.

Next, after coating and pattern formation with red and green luminescentmaterials shown in Table 1 and Table 2, respectively, by using anink-jet device 310 in the same way as Example 1, they were undergoneheat treatment under a nitrogen atmosphere for four hours to polymerizethe precursors in the compositions of the materials, thereby formingluminescent layers 306 (red) and 307 (green).

Next, a hole injection and transfer layer 308 made of polyvinylcarbazole (PVK) was formed on the entire surfaces of the luminescentlayers 306, 307 and the transparent electrode 303 by means of thecoating method.

Then, a blue luminescent layer 309 made of a distyryl derivative wasformed on the hole injection and transfer layer 308 by means of thevacuum deposition method.

Finally, an Al—Li electrode 311 having the thickness of 0.8 μm wasformed as the cathode by the deposition method, and thereby the organicEL element was manufactured. In this case, as described above, thecathode 311 was automatically separated and then insulated by theformation of the banks 304, the cathode was brought into a conditionthat is was patterned so as to correspond to the respective pixels 301,302 and 303.

Example 5

First, in the same way as Example 1, ITO transparent electrodes 801, 802and 803 and banks 805 were formed on a glass substrate 804 as shown inFIG. 4.

Then, after coating and pattern formation with the red, green and blueluminescent materials by discharging polymeric organic luminescentmaterials shown in Table 1 and Table 2, respectively, using the ink-jetdevice 809, they were undergone heat treatment under a nitrogenatmosphere at 150° C. for four hours to polymerize the precursors in thecompositions of the materials, thereby forming luminescent layers 806(red), 807 (green) and 808 (blue).

Next, the vacuum deposition was carried with the aluminum quinolynolcomplex to which the doping was not carried out to form the electrontransfer layer 811 having the thickness of 0.1 μm.

Finally, an Al—Li electrode 812 having the thickness of 0.8 μm wasformed as the cathode by the vacuum deposition, so that the organic ELelement was manufactured.

<Evaluation of the Luminescence Characteristics and the FilmCharacteristics of the Luminescent Layers>

The luminescence characteristics and the film characteristics of theluminescent layers of the organic EL elements which were manufactured inExamples 1 to 5 described above were evaluated according to thefollowing methods.

1. Luminescence Starting Voltage

A prescribed voltage was applied to the element, and the applied voltageat which a luminance of 1 cd/m² is observed was defined as theluminescence starting voltage [Vth].

2. Luminescence Life

The initial luminance after applying a stabilization treatment was setto 100%, and the changes in the luminance of the EL element weremeasured when subjecting it to continuous luminescence through supply ofa constant current of standard waveform, wherein the luminescence lifeis defined as the time until the luminance drops to 50% of the initialluminance.

In this case, the drive conditions for this experiment were set at 40°C. for room temperature, 23% for humidity and 20 mA/cm² for currentdensity.

3. Luminance (Brightness)

The luminance was measured, in which the current was set to 20 mA/cm².

4. Wavelength at Maximum Absorption

The wavelength at maximum absorption for each luminescent layer wasmeasured.

5. Stability in Film Formation

After heating the luminescent layer at 200° C. for 60 minutes,conditions for occurrence of defects such as cracks and deformation inthe respective luminescent layers were observed by a microscope.

The results of the evaluation were classified according to the followingmarks.

⊚ . . . Extremely favorable

O . . . Favorable

X . . . Unsatisfactory

The results of the evaluation are shown in Table 3 and Table 4.

As indicated in Table 3 and Table 4, the luminescent layers in Examples1 to 5 have excellent luminescence characteristics and excellent filmcharacteristics. In particular, when the luminescent layers were formedof polymer organic compounds, no defects were observed in theluminescent layers, and extremely favorable thin films were obtained.

In the above, the compositions for the organic EL elements and themanufacturing methods for the organic EL elements according to thepresent invention have been described according to the embodiments thatare illustrated. However, the present invention is not limited to theseembodiments, and for example, there may be inserted in the manufacturingprocesses for providing any intermediate functional layers between therespective layers. Further, the fluorescent dyes which are added forchanging the luminescence characteristics are not limited to thosedescribed above.

Further, a layer made of, for example, 1,2,4-triazole derivative (TAZ)may be provided as a buffer layer between the respective layers, therebyenabling to more improve the luminance, luminescence life and the like.

Furthermore, the manufacturing method for the organic EL elementsaccording to the present invention may include a further process inwhich surface treatment such as plasma, UV treatment, coupling or thelike are applied to the surface of the resin resists, the pixelelectrodes and the underlying layers in order to facilitate the stickingof the EL materials. Moreover, it is possible to apply the manufacturingmethod for the organic EL element of the present invention to themanufacturing method for the inorganic EL element.

The organic EL display device according to the present invention may beapplied to the low information field, such as segment display and stillimage display of whole surface simultaneous luminescence, for example,display of pictures, characters, labels, or may be utilized as a lightsource having point, line, or surface shape.

Industrial Utilization

As described in the above, according to the manufacturing method of theorganic EL element of the present invention, it is possible to explorerational design of the EL luminescent elements through a wide rangingselection of the luminescent materials. For example, through arbitrarycombinations of the luminescent materials and fluorescent dyes, it ispossible to obtain wide variety of display lights.

Further, by using the organic luminescent materials, it is possible toobtain the diversified designs of the EL element having high luminanceand long life.

Furthermore, by carrying out the pattern forming and arrangement of theluminescent layer for at least one color, the hole injection andtransfer layer and the electron injection and transfer layer by means ofthe ink-jet method, it is possible to set arbitrarily and precisely thesize and the pattern of the luminescent elements.

When a precursor, which can be conjugated (form a film) by thermosettingis used as a luminescent material, the latitude in the setting ofconditions such as viscosity can be expanded, and the adjustment of theconditions suitable as a discharge liquid for the ink-jet method can befacilitated.

Further, according to the manufacturing method for the organic ELelement of the present invention, conditions such as the film thickness,the number of dots and the like can be adjusted arbitrarily, so that itis possible to control readily the luminescence characteristics of theluminescent layers.

Furthermore, according to the ink-jet method, it is possible to movefreely the head on the transparent substrate, thereby enabling to forman element with an arbitrary size without restricting the dimensions ofthe substrate. Moreover, since required amounts of materials can bearranged at required locations, it is possible to maximally exclude theuselessness of waste liquid or the like. In this way, manufacturing of afull color display device with large screen size becomes possible at alow cost.

1. A manufacturing an organic EL device, comprising: forming a firstelectrode on or above a substrate, forming a hole injection/transferlayer on or above the first electrode, forming a luminescent layer onthe hole injection/transfer layer by discharging a luminescent materialcomposition from a nozzle toward the substrate, and forming a secondelectrode opposing the first electrode, a part of the materialscontained in at least one of the hole injection/transfer layer and theluminescent layer being in the state of mutual impregnation anddiffusing into the other layer at the vicinity of the interface betweenthe luminescent layer and the hole injection/transfer layer.
 2. Themanufacturing an organic EL device according to claim 1, at least onecompound constituting the luminescent material composition being aconductive polymer organic compound, in which π-electron of the doublebond is delocalized on the polymer chain.
 3. The manufacturing anorganic EL device according to claim 2, the polymer organic compoundbeing a polyparaphenylene vinylene, its derivative or a copolymer whichcontains at least either one of these compounds.
 4. The manufacturing anorganic EL device according to claim 1, the formation of the holeinjection/transfer layer by means of the ink-jet method being performedby discharging a hole injection/transfer material composition from anozzle toward the substrate.
 5. The manufacturing an organic EL deviceaccording to claim 4, at least one compound constituting the holeinjection/transfer material composition being a conductive polymerorganic compound, in which π-electron of the double bond is delocalizedon the polymer chain.
 6. An organic EL device, comprising: a substrate;a first electrode formed on or above a substrate; a holeinjection/transfer layer formed on or above the first electrode; aluminescent layer formed on the hole injection/transfer layer; and asecond electrode opposing the first electrode, a part of the materialscontained in at least one of the hole injection/transfer layer and theluminescent layer being in the state of mutual impregnation anddiffusing into the other layer at the vicinity of the interface betweenthe luminescent layer and the hole injection/transfer layer.